Television New Zealand has been accused of concealing research showing TVNZ7 had a growing audience at the time it was axed.

The state broadcaster has been forced by the Ombudsman to publish a survey carried out by Focus Research in May 2011, which showed 91 per cent of people who had heard of the public service channel believed it was important to New Zealand.

It also found awareness of TVNZ7 grew from 32 per cent in September 2008 to 74 per cent in May 2011. By then it was being watched weekly by more than half of all Freeview households, a number set to grow after the digital switchover.

The channel ended transmission in June after the Government decided not to extend $79 million in funding provided by the former Labour government to set up and run it for six years.

The lobby group Save TVNZ7, which estimates it would have cost about $16m a year to keep the station on air, first requested the research in July 2011 under the Official Information Act.

Save TVNZ7 spokesman Myles Thomas said TVNZ did not want the research made public then because axing the channel was still "a bit up in the air".

"TVNZ withheld this, knowing that if this got out into the public sphere it's quite likely that people would say ‘Hey?'

"Because they dillied and dallied and it's taken 15 months, they've managed to get it past the crucial time when TVNZ7 was closed down."

As a state-owned enterprise, TVNZ had a moral obligation to release the information.

Former broadcasting minister Jonathan Coleman announced in February 2011 that TVNZ7 would be canned. Two months later, he justified his decision by saying it had a weekly audience of only 207,000.

He admitted in May this year that the figure, which he said was provided by officials, had been calculated wrongly.

Mr Thomas said the research indicated that, by January 2010, more than 500,000 people watched TVNZ7 at least once a week.

It showed TVNZ knew Dr Coleman's figure was wrong, he said.

TVNZ spokeswoman Megan Richards said the research was carried out as part of its reporting back to the Government. "So the Government was fully aware of the contents of each survey."

TVNZ believed the research was commercially sensitive "despite the non-commercial nature of the channel as a whole".

The survey took place shortly after TVNZ6 was closed and its Kidzone programme transferred to TVNZ7, she said.